The concept of separation of powers is a cornerstone in Western political and governmental philosophy, aimed at ensuring balance and restraint in governance. This separation serves as a counterbalance to unchecked authority, preventing power from becoming absolute or oppressive. Jean-Jacques Rousseau’s perspective on the separation of powers, influenced by Montesquieu’s The Spirit of the Laws, emphasizes its necessity, sometimes explicitly and other times implicitly. Rousseau’s model divides authority into legislative, executive, and judicial branches. This study adopts a library-based research approach, gathering resources and applying analytical methods to conduct a comparative analysis of the separation of powers in the constitutional framework of the Islamic Republic of Iran and Rousseau’s philosophical thought. The central question explored in this research is whether Rousseau’s interpretation of the separation of powers aligns with its application in Islamic jurisprudence and the constitutional law of the Islamic Republic of Iran. The findings of this study suggest that Rousseau’s (and Western schools’) conception of the separation of powers fundamentally differs from the framework applied in the Islamic Republic of Iran. In Islamic principles, the separation of powers does not hold a foundational position, as power is regarded as a tool for humanity, not an end in itself, and is therefore not inherently corrupt or unrestrained. Furthermore, in Islamic thought, the concept of Ismah (infallibility) in the era of an infallible Imam prevents deviation and infringement on others’ rights. In the absence of the Imam, the Taqwa (piety) and justice of the Velayat-e Faqih (Guardianship of the Jurist) act as safeguards against despotism and political corruption. In contrast, Rousseau’s philosophy focuses on society and the general will of the people, emphasizing the creation of a system with a clear separation of powers and active participation of citizens in political decision-making. On the other hand, the Islamic Republic of Iran operates under the principle of Velayat-e Faqih, wherein executive, legislative, and judicial institutions function under the supervision of the Supreme Leader. This centralized system, due to its limitations on the separation of powers, may lead to an over-concentration of power in specific institutions. Both models reflect the values and conditions of their respective contexts. While Rousseau advocates for direct democracy and active public participation, the Iranian system prioritizes a centralized structure influenced by Islamic principles. Each approach carries distinct implications for the society it governs.